1. Field of the Invention
The present invention relates to solar water heating. This invention relates to solar water heating systems, including systems having solar collectors embodied in decorative structures. This invention also relates to methods of making solar water heaters and methods of heating water using solar energy.
2. Description of the Related Art
Solar water heating systems typically include a solar collector having a collecting surface that AS may be exposed to sunlight and a supply of water to be heated that is thermally coupled to the collecting surface. A portion of the sunlight impinging on the collecting surface is absorbed by it and raises its temperature; heat flows from the collecting surface into the water supply by conduction. The collecting surface is typically an exterior surface of a length of metal pipe that is filled with water to be heated. The length of pipe is often disposed in a serpentine path in a planar rectangular configuration in order to provide a relatively large collecting surface for the solar collector. Typically the heated water is circulated from the solar collector to some other location where the heated water, or the heat of the heated water, is to be used. Solar water heating systems are often configured with a solar collector disposed on the roof of a house or other building, and water is circulated between the collector and the interior of the building where the heated water may be used for space heating or a part of the building""s hot water supply. The amount of energy that can be received by a planar solar collector disposed in a fixed orientation is a strong function of time of day, peaking at local noon and falling sharply to zero no more than six hours earlier and later, assuming that the collector is oriented with its normal directed toward the meridian.
The design of solar collectors is usually dictated more by functional than aesthetic considerations. Locating a residential solar collector on the roof of a house rather than on the lawn adjacent the house may have a practical benefit in avoiding the solar collector being shadowed, or in using an existing structure to support the solar collector. However, the aesthetic consequence of such location may be merely to display an eyesore prominently on the roof instead of devoting lawn space to it.
Whereas prior art solar water heaters have apparently given little consideration to aesthetics, embodiments of the present invention are suited to inclusion of a solar collector in a decorative structure. In one embodiment, the present invention is a solar water heating system comprising a decorative structure and a coil of tubing disposed within the decorative structure, the coil having a helical shape and being oriented with its axis disposed generally vertically. In another embodiment, the present invention is a method comprising the steps of providing a coil of tubing, the coil having an axis and the tubing of the coil being radially spaced from the axis; disposing the coil in a location receiving sunlight with the coil axis oriented generally vertically; and causing fluid to flow through the coil. In another embodiment, the present invention is a method of making a solar collector for a solar water heating system comprising the steps of providing a supply of flexible tubing and a frame; securing a portion of the tubing to the frame; and rotating the tubing supply and the frame relative to one another so as to dispose a portion of the tubing in successive turns around the frame to form a coil.